The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Aircraft turbojet engines generate significant noise pollution. There is a strong demand to reduce the pollution, particularly given that the turbojet engines used are becoming increasingly powerful. The design of the nacelle surrounding a turbojet engine contributes in large part to reducing noise pollution.
In order to further improve the acoustic performance of aircrafts, the cells are equipped with acoustic panels that attenuate the noises due to the circulation of flows of air through the turbojet engine as well as the vibrations of the structures of the nacelle.
Acoustic panels are sandwich-type structures well known for absorbing these noises. These panels typically include a cellular acoustic structure that may assume the form of one or more superimposed cellular layers and each comprising cells (commonly called a “honeycomb” structure). The cellular acoustic structure is generally covered on the so-called outer face, i.e., the face radially furthest from the axis of the engine, by a skin that is impermeable to air, called “solid,” and on the inner face, i.e., the face radially closest to the axis of the engine, with an air-permeable perforated skin, called “acoustic.”
The acoustic skin is then assembled by positioning, then gluing the different skins and the acoustic structure on a mold having the required shape. The assembly undergoes curing in an autoclave so as to tighten the layers and polymerize the parts.
Such panels constitute acoustic resonators capable of “trapping” the noise and therefore attenuating the sound emissions toward the outside of the nacelle.
However, such acoustic panels may be damaged during the operation of the nacelle, requiring the repair or replacement of one or all of said panels.
Typically, the visible and accessible parts of the area of the acoustic panel to be repaired are cleaned before performing any repair. In fact, pollutant particles from the environment of the turbojet engine become deposited on said visible and accessible parts during the operation of the turbojet engine. The presence of such particles is detrimental for the durability of the future repaired panel.
However, it is not possible to eliminate all of the pollutant particles trapped in the cells. It is thus necessary for the repair technician to perform the repair without transferring any pollutant particles that may be present to the repair area.